Printing inks



United States Patent iiice PRINTING INKS No Drawing. ApplicationDecember 1, 1953 Serial No. 395,584

8 Claims. (Cl. 106-26) This invention relates to printing inks and moreparticularly to printing inks of the type designed to permit rapiddrying or setting of the printed impression by the application of heat,steam, liquid water, or a combination thereof.

Modern printing methods, and especially the operation of high speedrotary, web-fed presses, require that the ink be rapidly dried and boundto the paper so that the paper may be immediately printed on the reverseside with no transfer of ink to the guide bars, guide rollers, or secondside impression cylinders of the press.

In order to meet these requirements, it has previously been proposed toinclude volatile solvents in the printing ink and quickly vaporize thesolvent following printing by the application of heat to the freshlyprinted web, leaving the ink substantially dry and bound to the paper.

A difliculty heretofore experienced with inks of that type is that wheretoo volatile a solvent is used, the ink tende to dry prematurely on theink distributing rollers and printing plates, resulting in the paper webbeing picked or ripped by adhering to the tacky, partially dried ink onthe printing surfaces. On the other hand, if a solvent of low volatilityis used, excessive drying temperatures are required in order to obtainthe desired rapid rate of drying.

In order to avoid the necessity of using a solvent of too highvolatility, and yet obtain the desired printing speed in processes ofthis type, it has usually been necessary to effect the drying bysubjecting the printed matter to such high temperatures as tend toweaken the paper, usually of the order of 300 to 700 F., and frequentlyleads to interruption of the press-operation due to the breaking of theweb. Such operations are also costly because of the large amount of fuelrequired for heating the web to those high temperatures.

Further difficulties encountered in the selection of a solvent ofsuitable volatility have been the tendency of some vehicles to produceinks which permit too great a penetration of the ink into the paper, orwhich have poor transfer properties with respect to the inking mechanismor to the printing surfaces or to the web, or which fly off from therapidly rotating cylinders by centrifugal action, or in which the driedink film tends to rub or send off the printed matter.

It has more recently been proposed to set the ink on the printed matterby the application of steam, superheated steam, or even liquid water.However, the inks now being used in the art which set by the applicationof steam, the so-called steam-set inks, cannot be used with half-toneplates for long runs without causing specking or fill-up and thusprinting results of unsatisfactory quality.

It is an object of our present invention to provide inks having anitrocellulose base and which are press stable, i. e., will not dryprematurely on the inking mechanism and printing plates, but which canbe rapidly dried at substantially lower temperatures than thosecurrently required with presently available inks.

I set inks.

properties, and has good flow characteristics and excellent 2 A furtherobject is to provide inks which may be dried or set by application ofeither heat, steam, superheated steam, or liquid water, or a combinationthereof, to give satisfactory prints, with no specking or fill-up whenused with half-tone plates.

A further object is to provide inks having, in addition to theproperties just noted, superior transfer properties and a lowerpenetration into the paper than the inks currently used, and by whichthe pigment is bound more i firmly'to the paper and willnot rub or scuffoff. A still further object is to provide an ink of the type describedwhich, at high printing speeds, will cohere and adhere to the rapidlyrotating surfaces with less flying, or misting, than currently availableinks of this type.

These and other objects are attained by our present ever, nitrocelluloseof the type previously proposed is not soluble in the alkanediols usedin accordance with our present invention and is unsuited to our presentpurpose.

We have discovered, however, that nitrocellulose of the alcohol-solubletype, just noted, which has been nitrated to an extent not exceeding11.7%, e. g., l0.7-l1.7%, is

readily soluble in these alkanediols, either with or without heating,and provides an ink vehicle which, when compounded with suitablecoloring matter, results in an ink which is amenable to rapid drying orsetting of the printed impression either by the application of heat,steam, superheated steam, liquid water, or a combination of'these dryingand setting methods, and which avoids the previously noted difficultiesexperienced with steam- The resultant ink also has excellent transferprinting properties in all other respects. Further, the resultant inkhas good press stability, that is, it does not dry prematurely on thepress. Nevertheless, the printed imabout Mi second. However,nitrocelluloses of this type,

having a viscosity of /2 second, 5-6 seconds and 40-60 seconds have alsobeen found to be soluble in the alkanediols previously noted and may beused, with advantage, in accordance with our present invention. Theviscosity of the nitrocellulose does not appear to be critical so longas the particular nitrocellulose is soluble in the alkanediol or mixtureof the alkanediols used.

The proportion of nitrocellulose used is also subject to considerablevariation, depending upon the desired characteristics of the ink.Generally satisfactory results may be obtained using proportions ofnitrocellulose within the range of 2% to 25%, based on the weight of theink. Especially advantageous results have been obtained where theproportion of nitrocellulose is within the range of 2% to 10% by weightof the ink.

diol or 2-ethyl-l,3-hexand iol, or Z-methyI-ZA- entandiol.

We have found the 2 methyl-2,4-pentandiol particularly advantageous forthis purpose. However, other alkane- Petented Jan. 21, 1958 v diolshaving not more than 8 carbon atoms, ,0]: mixtures...

ties and jthat the inks'resulting from incorporating pig-- ments, orother coloring material, therewith? gives excela lent results inprinting with half tone plates. overzlongrv runs without causingspecking or fill-up, regardless Did.

the particular method usedin drying: or. setting themk 'Where desired,the nitrocellulose filmmay 'bev modified by including in the inkasubstantial proportion of. a:high

boiling material of the'type'known to. the art5for their,

ability to modify such films., For instance, we may. in;-

corporate in theink substantial proportions; of "dioctyl phthalate,tricresylphosphate, castor. oil, ,camphor, di-' butylsebacate, orotheresters, ethers; ether-esters-orre lated materials.

We have, with particular, advantage; incorporated .in the ink for thispurpose a substantial proportion, of the, order 0f5 to based on-theweight of the ink, ofxa' mixture of high molecular weight alcohols,ethers, and. esters, the alcohols of the mixture containing :8 :orgmorecarbon atoms per molecule and-the esters and ethersrof' themixture'containing 16 or more carbon-atoms pen molecule,.the mixtureboiling within'the rangeof-about 210 to-360. C. Such mixture of highboiling alcohols, ethers and esters have been used, withparticularadvanrage, in. conjunctiontwith nitrocellulose" of- Mr secondviscosity, and: of 10.7% to l1.'2%..nitrogen,content; and"2-methyl-.2,4v-pentandiol as the'alkanediol solvent-.1

The invention will be further illustrated by the:follo.W-' ing specificexamples. It*will be understood, however; that. these examples areby-wayof illustration :and .are not intended to be limitative;

Example I A vwet-process. Peacock. Blue inkzhas been prepared-,1. ashereinafter described, from the followingingredients and proportionsthereof:

Parts A second nitrocelluloset 1012-1 1.2%. nitrogen)2-methyl2,4.-pentandiol t .5 8:1 Pigment, 36.5.

cous fluid results; The solution of ith'e" nitrocellulose" mayibe aidedby heating, -where desired," but *usuallyjheating:.isnot necessary.Following-solutionof the =nitro= cellulose, .the pigment may be added"and mixedwith thevehicle; as by stiriingin' a conventional mixingdevicewThe resultant mass is then passed over anink'mill untilasmooththomogeneous' ink results.

was'crin'corporated :is illustrated by the following vexample f of aWet-process channel black' inkfi The, compounding of'the".severalifigredieirtsmay be efie'cted "as. previously, described; thetricresylphosp'hate being added with the-:alk'zinedidl;

WHere desired, other-resins, -solub1e- -inthe-airman;

or mixture of lthese-all2nediols may alsobe-in'cludedin the-inltf asillustrated lay/the. following examples;

4 Example III.

A wet-process chrome yellow ink has been prepared from the followingingredients in proportions thereof:

Parts M4 second nitrocellulose (10.7.-"1'1.2% nitrogen) 4.0 Zein 5.02,3-butylene glycol 30.5 2-methyl- 2,4.epentandiol 2515 Pigment 3510Example IV A weteprocessPhloxine;Red. ink has-been prepared from thefollowing ingredientszand. proportions thereof:

- Parts A, second nitrocellulose (l0.7l1.2% nitrogen) 4.4 A rosin-maleicadduct 9.6 2-methyl-2,4-.p entandiol 35.5 l,5-pentandiol" 2115 Pigments29.5

Example V A particularly advantageous .inkv inwhich the, nitrocellulosefilm is. modifiedsby, the-inclusion in. the ink. of

a mixture. ot-high.moleculanweight alcohols, ethers, and esters, .ofthe. .type, previously. described: herein, has. been. prepared as.follows, I

Bynthe procedure previously described,..-an inkvarnish wasprepared.from.therfollowingjngredients and the .PI'O'}, portions.thereof:

Parts.-v second,nitrocellulose (10. Z-11.2% nitrogen), 33Alcohol-ethereester.mixture: 13

Z-methyl-ZA-pentandiola 53 To. the :foregoing'yarnish; the pigment" andadditional alkanediol were addech'irr accordance withpthe followingformula:

Parts Above varnish 23 Z-methyl-ZA-pentandibl 42" Pigment and pigmentextender 35' As the pigmentextender, wenmaygforv instance-use, calciumcarbonate;., China .clay, blanc .fixe or-i thexlilcexWhere.desired,thelpigmentmaybe usedwithout extender.

The invention is not restricted as tothe typeiof pigment depending onthe properties of :the ink desired, such ;as

shade, viscosity, gloss, tinting strength, and the like, as:

is understood by-the art; Where vsdesired, .the ethanol.. added with thenitrocellulose may be eliminated'during the compounding of theQinlgz-forinstance,.by sol-vent in terchange. However, its presence .in. the.lfinisheddnkz is:

not usually objectionable;

Weclaim: 1. A printing ink. comprising a: coloring consisting I of1,2-propanediol; 2-methyl-l,2=propanediol; 1,5.-pentandiol,' I tandioland :2,3 -'butylene glycol, the proportron zof mtro cellulose beingwithin theirarrgez of ;-from::ab'out..2% torn I 25 basedzon the weightsof :theainkr 2. The printing ink .otclaimsl in whichxth'e nitroceleWhere a yellow i coloredninle is required,

:material dis-: persed in a vehicle=consistingessentially:ofnitrocellulosei. of the alcohol-solublewtype :containing not:more'tl1an1 11.7% nitrogen, dissolved in an alkanediol from the groupu"5 lulose is of Ms second viscosity having a nitrogen content within therange 10.7% to 11.2%.

3. The printing ink of claim 2 in which the nitrocellulose is present tothe extent of 2% to 10% by weight of the ink.

4. The printing ink of claim 3 in which the alkanediol isZ-rnethyl-Z,4-pentandiol.

5. The printing ink of claim 4 in which there is also incorporated asubstantial proportion of a mixture of high molecular weight alcohols,esters and ethers, the alcohols containing at least 8 carbon atoms permolecule and the esters and ethers containing at least 16 carbon atomsper molecule the mixture boiling within the range of 210360 C.

6. The printing ink of claim 1 in which there is also incorporated asubstantial proportion of a mixture of high molecular weight alcohols,esters and ethers, the alcohols containing at least 8 carbon atoms permolecule and the esters and ethers containing at least 16 carbon atomsper molecule the mixture boiling within the range of 2l0360 C.

7. The printing ink of claim 1 in which there is also incorporated aresinous material soluble in the a1kane diol.

8. The printing ink of claim 1 in which there is also incorporated ahigh-boiling film-modifier for the nitrocellulose.

References Cited in the file of this patent UNITED STATES PATENTS2,070,218 Kelly Feb. 9, 1937 2,437,908v Chiappe Mar. 16, 1948 2,537,531Hoyt Ian. 9, 1951 OTHER REFERENCES

1. A PRINTING INK COMPRISING A COLORING MATERIAL DISPERSED IN A VEHICLECONSISTING ESSENTIALLY OF NITROCELLULOSE OF THE ALCOHOL-SOLUBLE TYPECONTAINING NOT MORE THAN 11.7% NITROGEN, DISSOLVED IN AN ALKANEDIOL FROMTHE GROUP CONSISTING OF 1,2-PROPANEDIOL, 2-METHYL-1,2-PROPANEDIOL,1,5-PENTANDIOL, 2-ETHYL-1,3-HEXANDIOL, 2-METHYL-2,4-PENTANDIOL AND2,3-BUTYLENE GLYCOL, THE PROPORTION OF NITROCELLULOSE BEING WITHIN THERANGE OF FROM ABOUT 2% TO 25%, BASED ON THE WEIGHT OF THE INK.